Car Craft
Click here to find out more!

Oldsmobile 468CI - 500hp Engine Combos

Anyone Can Build

Photography by ,

Big-Block Chevy 496ci

See if you follow this logic. If you are going to make 500 hp with a production iron-block 454, you have to change the pistons, and that means you are going to have to tear the engine down. If there is any machining needed on the rods, including shot-peening, bushing, or repair, it costs almost the same to buy a good set of I-beam connecting rods with ARP bolts. In other words, you should. While you are there, a cast 4.250-stroke crank, instead of the stock 4.000-inch, is available for $259, and since the Rat is externally balanced, you are going to have to pay to balance the rebuilt engine anyway. The block notching should run about $125 in labor.

That gives you a 496 instead of a 454, and the guys at Coast Performance say combine that with a good set of aluminum heads, and it isn't 500 easy horsepower anymore, it's more like 600. Low cost is the beauty of building a Chevy. At $1,700 completely assembled, the Edelbrock heads are getting to the point where they are cheaper than rebuilding iron ones. But, if you knew what you were doing, you could rebuild a set of oval-port heads and do a little pocket porting to get the iron to flow like the aluminum. Assuming a core charge of $200 for factory iron, the price for parts and labor is around $1,200 total. So in this case, we would use the Edelbrock Performer RPM 454-0 heads. They are oval-port heads that take on some of the characteristics of a big rectangular port head without the loss of low-end torque.

Speaking with Chris Huff at Coast, we found that customers want the biggest engine they can afford, so Coast tries to find the late one-piece main-seal-style blocks and bores them 0.060-over. With the Edelbrock heads' 110cc chambers, a low-dome forged piston will give you around 9.5:1 so you can run it on pump gas.

At this horsepower level, you don't really need to give up low-end torque and driveability and run a single-plane intake. So Coast also recommends the Edelbrock RPM Air Gap 2-0. It offers a broad torque curve without giving up too much high-rpm horsepower.

Using a roller cam is an expensive proposition on a big-block, so the recommendation is an Elgin flat-tappet hydraulic with 234/244 duration at 0.050 with 0.553/0.578 lift ground on a 112-degree lobe separation angle. Coast always uses Probe Industries 1.7 roller rockers to enhance the valveguide life and tops the combo off with a Speed Demon 750-cfm carburetor.

PARTS LIST
DESCRIPTION PN SOURCE PRICECast 4.250-stroke crank 13766 Coast High Performance $259.00Elgin flat-tappet cam 14318 Coast High Performance 92.001.7 rocker arms 11645 Coast High Performance 289.00Edelbrock RPM heads 60459 Summit Racing 1,739.00 pr.6.135-inch I-beam rods 11663 Coast High Performance 299.00Edelbrock Air Gap manifold 7561 Summit Racing 235.88Speed Demon 750 carb 132-1402010DR Jegs 711.99

`SOURCE
Coast High Performance; Torrance, CA; 310/784-1010; coasthigh.com

Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!
0 comments
Car Craft